Storage array performance is one of the major factors contributing to the performance of the entire SAN environment.

If you encounter any problems with storage array performance, consult your storage array vendor documentation for any relevant information.

To improve the array performance in the vSphere environment, follow these general guidelines:

  • When assigning LUNs, remember that several hosts might access the LUN, and that several virtual machines can run on each host. One LUN used by a host can service I/O from many different applications running on different operating systems. Because of this diverse workload, the RAID group containing the ESXi LUNs typically does not include LUNs used by other servers that are not running ESXi.
  • Make sure that the read/write caching is available.
  • SAN storage arrays require continual redesign and tuning to ensure that I/O is load-balanced across all storage array paths. To meet this requirement, distribute the paths to the LUNs among all the SPs to provide optimal load-balancing. Close monitoring indicates when it is necessary to rebalance the LUN distribution.
    Tuning statically balanced storage arrays is a matter of monitoring the specific performance statistics, such as I/O operations per second, blocks per second, and response time. Distributing the LUN workload to spread the workload across all the SPs is also important.
    Note: Dynamic load-balancing is not currently supported with ESXi.